Sleep disturbance is a highly prevalent, disabling symptom in persons with cognitive impairment, particularly those in nursing homes. Their nocturnal sleep is light and fragmented with frequent awakenings. Persistent short napping episodes interfere with daytime functioning and nighttime sleep. Current interventions for sleep disturbance consist primarily of pharmacologic agents, but they have proven only minimally effective and have serious side effects. Feasible, cost-effective behavioral interventions that address the precipitating causes of disturbed sleep, such as daytime napping and reduced social and physical activity, are needed. Thus, the primary specific aim for this randomized controlled trial is to determine the effect of individualized social activity, progressive resistance training, combined individualized social activity and progressive resistance training, or a usual care control condition on nocturnal total sleep time and amplitude of the sleep-wake rhythm in nursing home residents with cognitive impairment. The secondary specific aim is to explore the roles of daytime napping, muscle strength, and physical activity in mediating the effect of progressive resistance training on nocturnal total sleep time. A total of 304 nursing home residents with cognitive impairment will be randomly assigned to receive individualized social activity such as games or music, high intensity progressive resistance training of the hip and arm extensors, combined social activity and progressive resistance training, or a usual care control condition for seven weeks. Polysomnography, actigraphy, direct observation, and one-repetition maximum testing will be used to measure the study outcomes at baseline and during week seven. The study follows a 2x2 factorial design, and will be analyzed using ANOVA with separate analyses for the two primary outcome variables of change in nocturnal total sleep time and amplitude of the sleep-wake rhythm. Path analysis will be used to explore the roles of daytime napping, muscle strength, and physical activity in mediating the effect of progressive resistance training on nocturnal total sleep time. This study will provide important new prescriptive data for clinicians on the usefulness of limiting daytime napping and promoting social and physical activity in elders with cognitive impairment and disturbed sleep.